1. Field of the Invention
The present invention relates to a processional travel control apparatus, which enables processional travel with a leading vehicle being driven by a driver and a plurality of vehicles automatically following the leading vehicle.
2. Description of the Related Art
In recent years when environmental problems have been highlighted, a technique for sharing electric vehicles within a certain area has been proposed to reduce problems of air pollution and traffic congestion. This type of technique for using shared vehicles requires a port (parking lot) for lending and returning the shared vehicles, and it is necessary to arrange a certain number of vehicles in each of these ports in respect to their utilization by users.
Generally, it is expected that ports for parking shared vehicles for this purpose will be provided in places where users converge, for example, in the vicinity of a station and the like. There is no problem if the usage time and usage frequency by the users are consistent in each port, however, if there is any variance, then there is a situation in which shared vehicles accumulate in a certain port. To solve this problem, a technique is proposed for arranging shared vehicles available for rent in appropriate ports as evenly as possible, whereby the vehicles are moved between ports by having a vehicle driven by a driver at the head of a procession and a plurality of driver-less vehicles following. (refer to Japanese Patent Application, First Publication No. Hei. 5-170008).
When travelling in a procession where succeeding vehicles follow a leading vehicle at the head, a system is used in which the succeeding vehicles follow the path of the leading vehicle. The leading vehicle sends vehicle speed, steering angle, vehicle position coordinates, direction, amount of torque required, brake pressure and the like, obtained from vehicle to vehicle communication, to the succeeding vehicles, and the succeeding vehicles follow the leading vehicle using the revised settings of the original vehicle's position and direction information obtained by radar.
Since the above-mentioned processional travel is used for moving shared vehicles between ports, it is necessary to receive information about the total number of vehicles and their sequence numbers in the procession, as communicated information from a control apparatus controlling the number of shared vehicles in a port, before travelling so as to form a procession. Accordingly, there is a problem in that it is impossible to form a procession outside a port (for example, on the travelling route between ports) where communicated information cannot be obtained from the control apparatus, or to cancel a procession, change the total number of vehicles and change the sequence numbers in the procession prior to travelling in a procession. Therefore, for example, in the case of collecting vehicles left in places other than at a port, travel in a procession cannot be performed.
Furthermore, there is a problem in that if a situation occurs where a vehicle in the procession needs to leave the procession while travelling in a procession, the number of vehicles in the procession cannot be changed after it has been formed, and the procession sequence cannot be modified while travelling in a procession.
Moreover, there is a problem in that, if procession cancellation, procession formation, change of the total number of vehicles and modification of the procession sequence numbers cannot be performed, it is impossible to rearrange the procession in an emergency stop in order to avoid danger or cope with a situation where the leading vehicle cannot move forward.
For example, if a location that the leading vehicle enters is under construction or has any obstacles, the vehicle cannot move forward further after it has entered, and inevitably has to move backward, a case with which the technique cannot cope. In this case where forward movement is impossible, since the procession is formed by a plurality of vehicles, it causes traffic congestion.